Mastering Stalls: How to Recognize, Prevent, and Recover Safely
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Aerodynamic stalls are caused by an excessive angle of attack. And while technically they can occur at any attitude, power setting, or airspeed, as a practical matter, they are likely to occur when operating at the edges of the normal operating envelope and/or while making abrupt control inputs. While it’s extremely important to understand what conditions can lead to a stall, how to recognize an impending stall, and correct recovery techniques, it’s not something to fear during your everyday flying.
Depending on design, airfoils used in general aviation, stall at angles of attack between 16 to 18 degrees. A wing will always stall at the same angle of attack; however, weight, and bank angle, power setting and load factor may change the speed or the pitch attitude at which the airplane stalls.
Stalls are not taught to make you proficient in performing stalls but are done to make you aware of and avoid an impending stall, or, properly recover in case you inadvertently stall the airplane. Practicing stalls will also help you learn the low airspeed flight characteristics of the airplane, and how to control the airplane at low airspeeds which is what you will encounter while maneuvering in the traffic pattern and approaching to land.
The test standards divide stalls into power off and power on. The power on stall simulates the takeoff and departure situations, and the power off stalls the approach and landing conditions. Whenever you perform any stall, the airplane must be at an altitude which allows the stall and recovery to be made without descending below 1,500 feet above the surface. This is an absolute minimum and stalls should be practiced higher, if at all possible. Also, the weight in the airplane must be properly distributed and balanced. This is always true, but it is especially important when practicing stalls. If weight is loaded too far forward, the airplane will stall at a higher airspeed; and if loaded too far aft, stall recovery may be difficult.
Power Off Stalls
The imminent stall recovery is made when the airplane is on the verge of, but not completely, stalled.
To begin, reduce power to idle and maintain altitude in level flight to slow the airplane to normal approach speed. As the airspeed slows into the white arc, extend the wing flaps. At the normal approach speed, lower the nose to the approach pitch attitude.
When the airplane is stabilized in the approach attitude and speed, begin to smoothly and slowly bring the nose up to an attitude which will cause a stall. This attitude should not be more than the normal climb attitude. The idea is to reach the imminent stall without having the airplane in an abnormally high pitch attitude.
The imminent stall recovery is made when the airplane is on the verge of, but not completely, stalled. This is when the first decay of control effectiveness or buffeting occurs because of the disruption of normal air flow over the flight control surfaces.
Recovery is made by lowering the nose, simultaneously applying full power while maintaining directional control with coordinated use of aileron and rudder. Because the airplane is not fully stalled, the pitch attitude only needs to be lowered to the point where minimum controllable airspeed, and thus control effectiveness, is regained. A pitch attitude slightly below level flight is usually sufficient to recover from an imminent stall.
As speed increases, slowly retract the flaps and establish a normal climb to the altitude specified by the examiner or instructor.
Imminent power-off stalls during turns should be made at 20 degrees of bank, simulating the turn from base to final. The imminent stall should be accomplished in approximately 90 degrees of turn. After establishing approach speed and flap configuration, start a 20-degree bank turn. Then, slowly and smoothly bring the nose up to the attitude which will stall the airplane.
During all turning stalls there is a tendency for the bank to increase. If the bank increases, the loss of vertical lift component tends to lower the nose. During the stall entry, use control pressures as necessary to prevent the bank angle from changing, keep the ball in the center, and keep the nose from dropping. Then, at the first sign of a stall, lower the nose, apply power, and level the wings. Right rudder pressure will be needed to offset the effect of the increase in power.
As speed increases, slowly retract the flaps and establish a normal climb to the altitude specified by the examiner or instructor.
The entry procedure for doing full stalls straight ahead with power off is the same as for the imminent stalls. For turning full stalls power off, the bank should be 20 degrees.
Full stalls require that the airplane be forced deeper into the stall, but recovery should be prompt when any of the signs of a full stall is experienced. Compared to the power on full stall, the power off full stall will provide fewer cues in that the airplane will not shake and buffet as much as in the power on stalls. Usually, the best clue is when the elevator control is full back and the nose pitches down.
The recovery procedure is the same as for all stalls. Reduce the angle of attack, add full power, and maintain directional control using coordinated rudder and aileron pressures. As you might expect, recovery from the full stall will require a lower pitch attitude to avoid the secondary stall and the altitude loss will be greater. As speed increases, retract the flaps- be sure that you have reached the best rate of climb speed before the final flap retraction.
Power On Stalls
The power on stalls duplicate, at a safe altitude, the accidental stalls that can be encountered during takeoff and climb out.
The power on stalls duplicate, at a safe altitude, the accidental stalls that can be encountered during takeoff and climb out. The stalls that simulate takeoff are entered in takeoff configuration at takeoff speed and power. Those that simulate the climb out are entered in climb configuration at climb airspeed and power. They are done straight ahead and in turns up to a maximum bank angle of 20 degrees. The pitch attitude for power on stalls has to be somewhat higher than for the power off stalls.
Also, the power on stalling speed will be slightly lower than the power off stalling speed. This is because the vertical component of thrust reduces the wing loading, and the propeller slipstream tends to maintain airflow over the center sections of the wings. To enter the power on stall, reduce power while maintaining altitude during the clearing turns. If simulating a maximum performance takeoff, the flaps should be extended if called for in the pilot’s operating handbook.
The airplane must be at the correct speed in the beginning in order to avoid an excessively high pitch attitude before the airplane stalls.
In the imminent takeoff stall, the speed is reduced to liftoff speed, and takeoff power is applied as the pitch attitude is raised to the normal climb attitude. The high power, low airspeed combination requires an increasing amount of right rudder pressure to keep the airplane in straight flight. Once the climb attitude is established, the nose is raised well above the climb attitude and held in that position until the first buffet or control effectiveness decay is felt.
At the first sign of a stall, recover by lowering the pitch attitude to slightly below level flight. Power is already at a maximum so the only available way to reduce angle of attack is with a reduction in pitch attitude. If flaps are extended, it will take a noticeably lower pitch attitude to recover from the stall. Retract the flaps if they are extended after reaching the best rate of climb speed and climb to the altitude specified by the examiner or instructor.
The full takeoff stall is identical to the imminent stall with the exception that the recovery is delayed until the airplane is fully stalled. The same entry procedure is used for the departure stalls with the exception that the airplane is in the climb configuration, at climb airspeed, and with climb power setting. As always when using a high-power setting at low airspeed, right rudder pressure is needed to keep the airplane straight.
The imminent stall recovery is made at the first sign of an impending stall, and the full stall recovery is started after the nose drops while holding full back elevator pressure, or an excessive sink rate or sudden loss of control effectiveness occurs.
Takeoff and departure stalls are also done in turns. After establishing the appropriate speed and configuration straight ahead, a shallow bank turn is started. The bank should not exceed 20 degrees and should remain constant as speed is reduced. Because of engine torque and “P” factor, turns to the left will tend to steepen, and banks to the right tend to decrease. However, during power on turning stalls to the right, you may find it necessary to use right rudder to overcome torque and “P” factor, and left aileron to prevent the bank from increasing.
The tendency in most airplanes is for the high wing to stall first, resulting in the airplane rolling toward the high wing. This is because, as the stall approaches, the airplane begins to mush and slip toward the low wing. This has the effect of blanking out the airflow over the raised wing, causing it to stall first, and the airplane will roll in that direction. If the turn is perfectly coordinated at the stall, the airplane should not experience any rolling moment, with the nose simply pitching away from the pilot.
Because of the loss of rudder effectiveness at low airspeed, it may not be possible to keep the ball centered in power-on stalls. If the ball is not centered, the airplane will roll away from the ball. If the ball is to the right, the airplane will roll to the left.
During the recovery, you should be prepared to use coordinated rudder and aileron pressure to stop the roll and level the wings. Remember, an airplane will always stall at the same angle of attack. The main factors which determine the angle of attack of a wing are, airspeed, weight, and load factor.
The indicated airspeed at which the airplane stalled is fairly consistent. The stalling speed in the turning stalls was slightly higher but the increase is so small that it is not readily noticeable. An increase in weight or an increase in load factor will cause the airplane to stall at a higher speed. Load factor is increased by steep turns, pull-ups, or any abrupt changes in the airplane’s attitude.
Accelerated Stalls
Stalls caused by an increased load factor are called accelerated maneuver stalls. As it’s used, the word accelerated does not mean speeded up, but that the stall has been caused by an increased load factor during a steep turn or an abrupt pitch change. Accelerated stalls should not be done with the flaps extended because of the risk of exceeding the maximum flaps extended speed in the stall recovery. Also, some airplanes have lower structural load limits with the flaps extended. To stay safely within the structural load limitations, they should be done at airspeeds at or below maneuvering speed and in most cases not more than 20 percent above the normal stall speed.
With power reduced, the airplane should be slowed to a speed one- and one-half times the normal stall speed in straight flight. When the proper airspeed is reached, a 45-degree banked turn is started with back elevator pressure used to maintain altitude. When the bank is established and the airspeed is 20 percent above the normal stall speed, back elevator pressure is briskly increased to bring about the stall.
At the stall, the rolling and pitching action is usually more sudden than you encounter in an unaccelerated stall. If the airplane starts to roll, power must be added and the back pressure released in order to recover before the wings can be leveled with coordinated aileron and rudder.
Practicing Stalls
Remember, stalls are practiced so that you can learn to recognize the approach of a stall and how to apply the correct actions to keep the stall from happening. Practicing flight at critically slow airspeeds, including stalls and slow flight, shouldn’t stop when you get your pilot certificate. Take a few minutes occasionally, to reacquaint yourself with the handling characteristics of the airplane at slow speeds. Experience the sight and sound cues of an impending stall, and how to prevent or recover from the stall. It’s a very small premium to pay for insurance you may never have to use.
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Great article…just one small observation. The discussion of recovery from full stalls begins with the statement that “the recovery procedure is the same as for ALL stalls.” This is correct for wing stalls, but not for tail stalls, so technically it does not apply to all stalls. Again, just a small observation. Overall, terrific article! Thanks!
This is a very good article. However, I am wondering why we don’t EMPHASIZE in training HOW the pilot CONTROLS Angle of Attack? My understanding is the elevator (control yoke/stick) Position controls AoA (stick back=AoA big, Stick forward=AoA little), if this is incorrect, please chime in!!
The “Pilots Handbook of Aeronautical Knowledge,” page 5-3 states “Any time the control yoke or stick is moved fore or aft, the AOA is changed.” That is the only bluntly stated reference I can find in FAA documents (or nearly all commercial documents). In fact, AC 61-67C, “Stall Spin Awareness Training,” NEVER mentions “How” the pilot Controls AoA., but the AC was written to provide guidance for avoiding stalls and spins.
I teach control yoke distance from the instrument panel as a close indication of AoA (yes, CG, propwash, configuration have some impact how many inches this is).
When discussing G in a turn and increased stall speed, I teach it’s not the Roll, but the Pull that impacts G and stall speed.
Am I wrong? Comments please.
You are not wrong, the more you pull back on the stick/yoke, the harder you’re asking the wing to work as you increase the angle of attack. And of course, there is a limit as to how hard the wing can work which is the point at which the wing will lose a lot of lift and stall.
Thanks for the response, I knew I was correct, but hoped to get some dialog going to emphasize how the pilot controls the AoA, stall, and recovery with one simple step: yoke/stick fore-aft placement.
We still see many pilots (including ATPs) not understanding this simple concept and crashing. Catharine Cavagnaro had great article in AOPA this month, also about proper stall recovery.